1. Field of the Invention
This invention relates to spray apparatus and is more particularly directed to automated apparatus for roadside spraying of herbicides which is mounted on a detachable frame fixed to the front of a vehicle and controlled by the operator of the vehicle and comprises a series of independant switches mounted on a control panel in the drivers compartment of the vehicle within reach of the driver, which switches control a plurality of solenoid valves and thus the spray through nozzles mounted on the detachable frame.
2. Description of the Prior Art
Maintenance costs of highway systems have escalated dramatically in the recent past. Such escallation is due in part to the constant extension of the state and federal highway systems and in part to the constantly increasing cost of labor. A significant item in highway maintenance cost is the control of vegetation growing along the highway right-of-way and the need to prevent vegetation from growing into shoulders and the roadway proper.
Mechanical cutting of such vegetation is possible along the right-of-way but is not satisfactory for keeping the shoulder and roadway free of vegetation. The latter has been achieved primarily through use of chemical herbicides. Herbicides used primarily for control of broadleaf weeds and some unwanted grasses are used extensively on the right-of-way, leaving desirable grasses alive for erosion control. Such herbicides are termed selective in that they do not kill the desirable grasses. Herbicides used primarily for control of vegetation on shoulders and in the roadway are intended to kill all vegetation and hopefully prevent its regrowth for some period of time. Such herbicides are termed residuals if they are able to prevent regrowth for some time. For the purposes of this description the treatment of vegetation with contact herbicides and residual herbicides is much the same and will be included in the description of the application of residual herbicides.
Prior art methods of applying herbicides fall generally into two generic procedures. Those are application from hand operated sprayers and from mechanized mobile spray apparatus. The former procedure is used almost exclusively for residual herbicides because of the precision of application necessary with residual herbicides. However, hand operation is slow, entails very high labor cost, requires a large number of individuals to keep pace with the miles and miles of roadside, and is limited to application of only the single herbicide contained in the spray tank.
Mechanized apparatus, such as that disclosed in U.S. Pat. Nos. 2,995,307; 3,544,009 and 3,913,836 is designed and used primarily for the application of selective herbicides on the area between the shoulder of the highway and the edge of the right-of-way. Such equipment lacks adequate control of speed, rate of application and regulation of the distance between sprayhead and ground to achieve the precision of application necessary for residual herbicides. If applied too liberally there will be run-off of residual herbicides and desirable vegetation of the right-of-way will be killed or damaged. If applied at this low a rate the residual herbicide will not prevent the growth of vegetation on the shoulders or in the roadway. Such mobile sprayers still require the use of two men in many instances and require two trips down each side of the roadway if they are used for the application of both selective and residual herbicides. Other known U.S. patents are: U.S. Pat. No. 3,565,341; U.S. Pat. No. 378,672; U.S. Pat. No. 2,655,405; U.S. Pat. No. 3,994,310; U.S. Pat. No. 2,974,875; and U.S. Pat. No. 3,826,431.
The apparatus of this invention permits for precise application of herbicides as is necessary for residual herbicides. The application can be made by a single operator of the vehicle. By use of the dual system embodiment both residual and selective herbicides can be applied by a single operator with finger-tip control to avoid run-off of the residual herbicides and to prevent residual herbicides being sprayed around trees or other desirable vegetation.